A comment in boost/iterator.hpp and boost/detail/iterator.hpp mentions that
the files are obsolete and will be deprecated. All they do is pull some types
from namespace std into namespace boost.
boost/iterator.hpp was implicitly dragged in via boost/operators.hpp, from which it was removed in cb6500161b. It's not needed anyway, all it does is map boost::iterator to std::iterator.
for handling vc6/7 deficiencies with iterator_traits.
Fixed a bug in iterator_facade which was causing incomplete types to
be passed through is_convertible.
Reinstated libs/utility/iterator_traits_test.cpp
[SVN r19840]